Experiments are proposed to study the process of visual transduction at several levels. To understand the photochemical processes involved with the visual pigment's chromophore we will study the excited state absorption spectra of small polyenes. This should tell us the state ordering of small polyenes which will help in understanding their photochemical properties. A second level study will involve visual pigments themselves. Here transient spectroscopy will be used to characterize the photolysis intermediates of rhodopsin as well as modified rhodopsins in order to understand the changes which occur in this protein upon excitation with light. Finally, we will study the transduction mechanism at the level of the interactions among various proteins found in retinal rod disk membranes. Here we will use light scattering and a phototagging procedure to determine what proteins interact with rhodopsin at various stages during the transduction process in order to understand the nature of the enzyme cascade ultimately responsible for transduction.